Brake system



May 2, 1939-* H. K. WEIHE i 2,156,415

BRAKE SYSTEM Filed June 30, 1956 5 Sheets-Sheet l May 2, 1939 H. K. WEIHE 2,156,415

BRAKE SYSTEM Filed June 30, 1936 3 Sheets-Sheet 2 A fm2.,

May 2, 1939- Hf KQWEIHE 2,156,415

` l BRAKE 'SYSTEM Filed June 50, 1956 5 Sheets-Sheet 3 ff Fay 6.

` f Hm/ Fly-'7- l C@ y Patented May 2, A1939 UNITED STATES PATENT OFFICE Application June so, i936, serial No. 88,202 In Germany July 1, 1935 (Cl. 18S-152) 6 Claims.

The invention relates to a hydraulic brake system, more particularly for' automobiles. In such hydraulic systems it is very important that no airshould be able to enter the fluid circuit. Ant7 noticeable accumulation of air in the active part of the brake system is known to produce, when the brakes are applied, a strong buffer action, which has an unfavourable effect on the development ofthe necessary brake pressure, so that m reliable operation of the brakes becomes doubtful, whichin some circumstances may have disastrous results. In order that no air may enter the brake system it is necessary to take care that the initial pressure in. the circuit, which is adl 5 justed to a denite value, should always be maintained. When the piston in the main brake cylinder returns to the position of rest (original position), no reduced pressure should occur in the main cylinder, but this may easily happen if` the piston in the main cylinder moves back more quickly than the brake uid can ow back out of the wheel brake cylinders and the pressure pipes. At the high pressure which is developed in applying the brakes it is necessary to allow for small leakage losses, which result in a reduction of the originally adjusted initial pressure in the circuit. Care must therefore be taken that any loss in fluid in the circuit should be immediatelycompensated. l

The invention has the .object of producing a relling device for a hydraulic brake, which,l in a completely satisfactory and reliable manner, en-

' sures that any loss of fluid, after each braking .operation and also while the brake is in the state` of rest, shall vbe immediately compensated. According to the invention the refilling devicev of the hydraulic brake consists of a positively driven auxiliary pump which, during the whole braking operation, draws from the reservoir a definite excess quantity of uid, which, when the pressure piston of the main cylinder returns to the state of rest for brakes in the off position, is forced by the auxiliary pump into the brake circuit, the 5 amount of liquid above that required for refilling passing back to the reservoir through a return ilow aperture. By means of such an arrangement the whole brake pressure system is kept v'.ggmstantly lled with the necessary quantity of 5 Iliquid, so that the occurrence of a reduced. pressure in the brake system is reliably prevented. In other words, the predetermined initial pressure in the whole brake system in the oif position remains constantly at the same value. The

55 entry of air into the system is thereby completely impossible, so that a proper working of the brake is at all times ensured.

Various constructionalforms are possible for carrying the invention into effect. Further details of the invention are described together with 5 these, as will be seen from the following description.

In the accompanying drawings four constructional examples of the invention are illustrated diagrammatically. f

Fig. 1 is a side elevation of the brake system with an auxiliary pump arranged at right angles to the main brake cylinder in section;

Fig. 2 shows the second construction of the main brake cylinder with the auxiliary pump also l5 in section;

Fig. 3 is a vertical section on the line V-V o theconstruction in Fig. 2;

Fig. 4 shows the third constructional example of the new brake system in perspective; 20

Fig. 5a shows the holder for the driving member of the .auxiliary pump in plan;

Figure 5b shows the same holder as in Fig. 5a in side elevation;

Figs. 6 and 7 show -a constructive detail of the 25 invention'.

In the construction according to Fig. 1, l is the main cylinder of the brake system with the pressure piston 2 Vreciprocating therein, which, at the end nearer the pressure space of the cylinder has a packing sleeve 3 consisting of flexible soft material, for example, rubber, which is pressed by the piston return spring l against the end of the piston 2. .The piston 2 is driven by the pedal 4 pivoted at the point 5 which, at its lower end, is pivoted to the thrust rodA 6, the front rounded end of which engagesina deep pocket on the back 'of the'piston 2. At the outlet port 20 of the cylinder is attached the pressure con- 40 duit I which leads in the usual manner tothe Wheel brake cylinders R of the vehicle, only one of which is illustrated for the sake of simplicity. With the main cylinder l a second cylinder 'l is connected,.which is arranged at right angles to the main cylinder and is preferably cast in onev piece therewith. In this additional cylinder 1 is the slidable piston 8, which on its pressure side also has a packing sleeve 9. The piston 8 is acted upon by-'a .compression spring l0 which 50 engages the end of the piston. At the centre of the end of the piston is attached a tension cord Y Il which'is guided over a pulley I2 and is connected withrthe pedal 4 at the point 4. The auxiliary or .relling cylinder 1 is surrounded 55 concentrically by the uid reservoir I5, which is closed at'the top by means of the removable` cover I4 having in the centre a hole I4. Between the reservoir I4 and the pressure space 'I' of the cylinder .'I there is provided a; suction valve, for example a non-return ball valve I5, which is preferably arranged near the end of the pressure space 1', as is shown in Fig. 1. pressure space 1 is further in-communication with the pressure space of the main cylinder I througha conduit I 9 passing lengthways through the wall of the main cylinder I. In this conduit is provided a pressure valve I6 in the form of a spring loaded ball valve. The conduit I9 opens at the outer end near to the outflow opening 20 in the main cylinder I. Immediately in front of the packing sleeve 3 a conduit (overow conduit) 22; provided in the wall of the cylinder I, branches oif, to which is connected a rising tube 22' opening near the highest point of the reservoir I4. In the conduit 22, which communicates with the reservoir through the rising tube, there is provided a regulating member (overflow valve) I1, which determines the initial pressure in the main cylinder and may be in the form of a pressure valve which is loaded lby the spring I8, the tension of which is adjusted to the value of the initial pressure inthebrake system. 'Ihe closing force of this valve is somewhat weaker than the return springs F of the brake blocks B of all the wheels.

The brake device illustrated in Fig. 1 acts as follows:

In the off position of the brake system .the various parts take up the positions shown in Fig. 1. If the pedal 4 is depressed the piston .2 is moved forwards in the cylinder I by the thrust rod 6, that is in the direction of the outlet 20. The pressure thus exerted on the iiuid in the cylinder is transmitted through the conduit I to the wheel brake cylinders R, so that the brake blocks B are forced against the brake drum 'I of each wheel. 'Ihe opening of the retiun conduit 22 which, in the brake off position is immediately in front of the packing sleeve 3,

is covered during the forward movement of the piston 2, rst, by the edge of the sleeve 3 and then by the piston itself, so that no fluid can be forced out of the cylinder through this conduit. The spring loaded valve I6 is additionally forced against its seating by the fluid pressure in the cylinder I so that also the conduit I9, between the pressure space 'I' of the auxiliary pump and thecylinder I, is closed. While the piston 2 is pressed forwards in the cylinder the piston 8, in the cylinder 1, is drawn back by the .cord II, attached to the pedal 4, against the pressure of the spring III so as to enlarge the working space 'I'. As a result, fluid is drawn from the reservoir It, through the 'valve I5, mtu

the space 1' in front of the piston 8 of the pump.

As soon as the brake pedal 4 is released, that is, returns to its position, the spring I9, which was compressed when the piston 8 was moved by the cord II, fo'rces the piston 8 back to its initial position, as shown in` Fig. 1.- The :duid

in front of the piston s of the pump is then forced vthrough the conduit I9 and the non-return valve I6 into the main cylinder I. On account of the ow of uid into the pressure space of the cylinder I the quantity of fluid, which may have been lost during the braking operation, isimmediately replaced, so that the pressure in the brake system can never drop below the value of the necessary initial pressure. The excess quantity of The' uid which iiows into the pressure space of the cylinder I under pressure is forced through the overow valve I1, which opens vwhen the initial pressure is exceeded, into the return conduit 22 and further, into the rising tube 22', from which this fluid finally flows into the reservoir I4.

The ow of the uid is indicated by arrows in Fig. 1 so as to make the process more readily understood.

'I'he process described shows that every loss of uid in the brake system is 'immediately made up after the braking operation by the introduction of fresh fluid under pressure. It is thus impossible for detrimental air spaces to form in the brake system. The initial tension in the system is thus always constant, so that the outside air finds no opportunity to enter the system. The most important feature is that the auxiliary pump performs its function, even when the vehicle is out of operation for a long time. The

compressed, spring I0 will then force more uid into the main cylinder if any loss of uid occur. The arrangement of the rising tube 22 in the reservoir I4 has the advantage that the air bubbles, which are forced into the return passage 22 out of the main cylinder I when the excess uid ows back to the reservoir I4, will be separated when the fluid iiows over the edge of the upper end of the rising tube, that is at the highest'point of the reservoir. This prevents the air bubbles being drawn into the pressure space 1 ofthe pump 1 when iiuid is drawn out of the reservoir I4 and passing from the pump into the main cylinder 4I.

In Figs. 2 and 3 a second construction according to the invention is shown, in which the main brake cylinder 42 andthe pressure cylinder 49 ofthe auxiliary pump are arranged horizontally one abovethe other. between the two cylinders. The main brake cylinder 42 with the pressure'piston 43 movable The reservoir 41 is placed therein and the packing sleeve 44 form the lower part. At the outlet end of the main' brake cylinder there is likewise provided a packing sleeve 45 with central opening. In the initial position of the piston 43 the packing sleeve 44 in front of it covers with its resilient lip-shaped edge the ne lateral opening 46 in the main brake cylinder, which forms a connection between the main cylinder and the reservoir 41. The other packing sleeve 45 closes with its yielding edge the lateral hole 48a near the outlet end 63 of the main brake cylinder which leads through the adjoining passage IIIA to the refilling cylinder 49 placed above the reservoir 41. In the' refilling cylinder, which communicates with the reservoir 41 through thesuction passage 50a and the suction valve 50, 5I is the delivery member for. the reflllworking end a packing sleeve` 52. The piston 5| is acted upon by a return spring 53 engaging with its rear side the tension of which can be adjusted to the desired value by means of the adjustable abutment (screw member) '54. The piston 43 0f the cylinder 42 is driven through the thrust rod 55 by the brake lever 51, which moves in the di rection of the arrow A about the pivot point 56. On the brake lever there is a lug 59 for driving the connecting rod 58 which actuates theh reiilling piston 5I in the suction direction. The connection between the rod 58 and the driver 59 is such, that the connecting rod, or the brake lever, is only able to drive the refilling piston in the suction stroke direction, while the return movement of the piston 5I is eiected independently of these driving elements. For this purpose the connecting rod 58 has a ball head 66 at the end nearer to the brake lever, while in the other direction there is no engagement point onthe connecting rod for the driver 59, so that the connecting rod 58, and thereby the piston of the relling pump, can only be driven by the brake lever 51 in the direction of the arrow. The pedal 51 in theoif-position rests with the part 51' against a resilient stop, which is formed for example by the spring 62, which is mounted in the eye 62.

This braking device operates as follows:

When the brake lever 51 is moved in the direction of the arrow A the piston 43 is moved forward in the cylinder 42 in the'direction of the outlet 63. It then forces the fluid in iront of it into the pressure conduit (not illustrated), and,

further, into the wheel brake cylinders. 'I'he resilient edge of the sleeve 45 bears firmly against the opening 48a so that this is tightly closed from the cylinder 42. During the forward move-` ment ofthe piston 43 the piston 5|, in the cylinder 49, is drawn backwards by the driver 59' on the brake lever, that is in the direction of the brake lever, and thereby draws fluid fror the reservoir 41 through the passage 50a and the suction valve 50 into the refilling cylinder 49.

As soon as the brake lever 52 is released, the piston 5|, under'the influence of the compressed spring 53, forces the uid in front of it through the passage 48 and the opening 48a into the pressure space of the cylinder 42, simultaneously forcing back the edge of the sleeve 45. The ex,- cess fluid forced into this pressure space is returned to the reservoir 41 through the opening 46, which is opened by the sleeve 44, when the initial pressure in the brake system is exceeded on account of the yielding of the piston 43. The yielding of the piston 43 beyond its normal rest position is made possible by the resilient brake lever stop 62.

In this brake arrangement a separate return spring for the brake lever or the main pressure piston may be dispensed with. The taking off of the brakes is eiected apart from the brake block springs by the strong back pressure of the i'luid, which is produced by means of the return spring 53 acting on the rear side of the relling piston If it is desired that the refilling piston 5| should draw in a considerable quantity of relling uid after the brake lever 51 has moved only a small distance, the reiilling cy1inder49 is preferably constructed with a greater diameter than the cylinder 42.

'Ihe arrangement of the reservoir 41 in Figs. 2 and 3, between the main pressure and the auxiliary cylinders, makes it possible to construct a brake system which is comparatively small. and takes up little room and is therefore easily accommodated. v

In Fig. 4 a third constructional form ofthe invention is illustrated. In this case the main brake cylinder 42 and the auxiliary cylinder 49, which may both be constructed as in Fig. 2, are arranged horizontally side by side. The operation of this form of the invention is similar to that described hereinbefore relating to Figs. 1 to 3. The reservoir 41 is again placed between the two cylinders. With this arrangement a low unit is obtained. In-the cylinder 42, which forms the 4 main brake cylinder, is the pressure piston 43. The cylinder A49 contains the piston 5| and forms the relling pump. The two pistons are driven in opposite directions in accordance with the invention.l The vpiston 43 in the main cylinder is connected through the piston rod 55 with the brake pedal 51, which is rotatably mounted on the coupling shaft 13 and to which the piston rod is pivoted at 65. The piston 5| of the relling pump is engaged by the rod 58, constructed preferably of wire, and pivoted to the driving member 66, which is in the form of` a double lever. The double lever 66 is mounted in the holder 68 so as to be rotatable about the pin 69 which is arranged in a vertical plane. The holder 68 consists of a fork head with a short threaded extension (see Figures 5a and 5b) which is screwed into the end wall of the cylinder block between the two cylinders 42, 49. The threaded hole lies between the two cylinders 42, 49. The arm of the double lever 66 which is further from the rod 58 of the refilling pump is connected with the piston rod 55 of the main pressure device so as to be caused to move therewithin the direction of the braking stroke, the double lever being driven by a stop in the piston rod 55. The driven lever arm lies either as shown in Fig. 6 in an aperture (longitudinal slot) 1|- of the piston rod 55 or the lever arm is forked at its free end and engages over the piston rod 55, as shown in Fig. 7. The stop on the piston rod 55, which effects the driving of the swinging lever 66, is formed in Fig. 6 by a roller 12lmountedin the slot 1|. In Fig. 7, on the other hand, two rollers 12 are provided on the outer side of the piston rod 55. When the brake pedal is depressed, one arm of the swinging lever bears against this roller, or rollers, so as to be driven by the piston rod 55 and thereby turned about the vertical pin 69 in the holder 68. In view of the vfact that when the piston 43 is forced into the cylinder 42, the piston rod 55 is moved a certain distance out of the horizontal plane, which would result in a seizing of the lever 66 in the slot 1| of the piston rod 55 or of the latter in the forked arm of the swinging lever (Fig. 7) the holder 68 is readily rotatable about its threaded axle. the threaded pin according to Fig. 4 on the holder not being completely screwed into the threaded hole. In this Way the lever 66 is able to follow the movement of the piston rod 55 in the vertical plane when the brakes are applied, so that there is no seizing between the said parts.

The braking larrangement in Fig. 4 is further arranged in such a manner that the refilling pump or its driven member 66, can also be actuated independently of the brake lever 51. The horizontally mounted swinging lever is extended beyond the piston rod 55. This extended end of the free arm-of the swinging lever co-operates with a cam-like driver 14 which is fixed on the coupling shaft 13 beside the Abrake pedal 51. By depressing the coupling pedal 15, which is keyed or otherwise secured on the outer end of the shaft 13, the cam 14 is caused to bear against the lever 66'and rotates the latter about the pin 69, at the same time driving the piston 5| of the reiilling pump. Preferably the outer end of the extended lever arm is of round cross-section so that a pulley or roller 16 may be mounted thereon. The Iarrangement described acts as follows: When the` pedal 51 is depressed the piston rod 55 and consequently the piston 43, are moved further into the interior of the cylinder 42. The pistonrod 55 drives the lever 66, which bears against the roller-12 (Fig. 6) or against the two -external rollers (Fig. 7) of the piston rod 55.

'- nected with the piston rod 58 draws the piston 5| of the pump out of the interior of theI cylinder t9 a distance corresponding to the swinging movement of the pedal 57. The pump thereby draws fluid'out of the receiver 4l. When the brake pedal l is released the piston 5l of the pump, by means of a stressed compressed spring or the like (compare Fig. 2), forces the previously drawn-in uid through a pressure valve or the like, which is not shown in the iluid pressure system.- 'Ihe quantity of iluid exceeding the amount required for refilling passes through a return valve back to the reservoir 4l.

If, on the other. hand, the clutch pedal is depressed, the shaftv 13 mounted in the clutch casing S rotates, driving the cam 14. The brake pedal 51, which is mounted loosely on this shaft, remains in its original position. 'I'he cam I4 bears against the roller i6 and thereby against the long arm of the lever 66, which again is swung about the pin 69 and drives the piston 5| of the refilling pump. The piston 43 `in the main brake cylinder l2 remains in its initial position since the swinging lever 66 when moving towards the cylinder block nds no abutment on the piston rod 55.

In this way the relling pump is driven automatically whenever the driver works the clutch or brakes. It is thus always certain that the uid pressure system will be lled and that the necessary initial pressure in the brakes `will be available. In other words a braking arrangement is available which is always completely readyfor 4use and reliable.

, The lever 66 actuating the refilling pump may naturally also be connected with another driving member. For example a cord 'Il or the like couldl engage with one long arm of the lever, which would be connected with any moving part of the vehicle, which would then actuate the reillling pump in the manner described independently of the operation of the brakes.

In case it is impossible for reasons of space to extend the horizontally mounted lever 66 beyond the piston rod 55, the refilling pump can also be driven independently of the operation of the brake by the rod 58, being connected to another drivin'g member.

'I'he constructional examples described have shown that the invention can be carried into eiect 4in numerous ways and does not involve any particular construction and arrangement of the various parts of the brake pressure system. The

only essential feature is that in the braking operation a sufficient quantity of uid is drawn out of the receiver, which when the brakes are released, is forced under pressure into the brake pressure system, while the excess quantity of fluid determined by the initial pressure in the circuit can flow away from the circuit again through yan overiiow valve or similar device. In

0 this way there is obtained complete certainty that the brake system is always illed with the neces'- sary amount of iiuid and that any changes of volume due to leakage, drop in temperature and so forth, are always immediately compensated.

Fluid will also ilow out of the brake system through the overflow valve if the pressure in the system should rise owing to external temperature influences or for other reasons.

What I claim is:

1. A hydraulic brake system for vehicles ofv a conduit between said pump and said cylinder,

inlet valve means between said conduit and cylinder, a conduit connecting the cylinder to the reservoir and outlet valve means between said cylinder and said second mentioned conduit.

3.' A hydraulic brake system, including a main cylinder, a piston therein, means for driving the piston, a reservoir, a re-lling pump, a positively driven spring-loaded piston therein, a conduit between said pump and said cylinder, inlet valve means between said conduit and said cylinder, said cylinder having an aperture in its wall communicating with said reservoir, means on said cylinder piston for covering said aperture, and a resilient stop for saidcylinder pistonv driving means.d

4. A hydraulic brake system, including a horlzontally arranged main cylinder, a piston therein, a horizontally arranged re-lllng pump, a spring-loaded piston therein, swingable two armed lever for operating both pistons.

5. A hydraulicbrake system, including a horizontally arranged main cylinder, a piston therein, a horizontally arranged re-lling pump, a springloaded piston therein, a two-armed lever for operating both pistons and relatively stationary supporting means for said lever.

6. A hydraulic brake system for vehicles of Vany type, including a. main cylinder, a piston slidable therein, means for operating said piston, a refilling pump communicating with said main cylinder, a spring loaded pistoi within said pump and means connecting said spring-loaded piston to the clutch lever of the vehicle, said springloaded piston acting to inject f luid into the main cylinder when the clutch and brakes are released. KURT WElJE.

and a horizontal 

